Objective. The spatial resolution of an implantable neural stimulator can be improved by creation of virtual channels (VCs). VCs are commonly achieved through synchronized stimulation of multiple electrodes. It remains unknown whether asynchronous stimulation is able to generate comparable VC performance in retinal stimulation, and how VC can be optimized by re-designing stimulation settings. This study begins with exploring the feasibility of creating VCs using synchronous and asynchronous epiretinal stimulation, and ending with predicting the possible VC performance with a thorough exploration of stimulation parameter space. Approach. A computational model of epiretinal dual-electrode stimulation is developed to simulate the neural activity of a population of retinal ganglion cells (RGCs) under both synchronous and asynchronous stimulation conditions. The interaction between the electrode and RGCs under a range of stimulation parameters are simulated. Main results. Our simulation based on direct RGC activation suggests that VCs can be created using asynchronous stimulation. Two VC performance measures: 1) linearity in the change in centroid location of activated RGC populations, and 2) consistency in the size of activated RGC populations, have comparable performance under asynchronous and synchronous stimulation with appropriately selected stimulation parameters. Significance. Our findings support the possibility of creating VCs by directly activating RGCs under synchronous and asynchronous stimulation conditions. This study establishes the fundamental capability of VC creation based on temporal interactions within the RGC population alone and does not include the effects of potential indirect activation of any surviving inner retinal network neurons. Our results provide theoretical evidence for designing next-generation retinal prosthesis with higher spatial resolution.

客观的。植入式神经刺激器的空间分辨率可以通过创建虚拟通道 (VC) 来提高。VCs 通常是通过多个电极的同步刺激来实现的。目前尚不清楚异步刺激是否能够在视网膜刺激中产生类似的 VC 性能，以及如何通过重新设计刺激设置来优化 VC。本研究首先探索使用同步和异步视网膜前刺激创建 VC 的可行性，最后通过对刺激参数空间的彻底探索来预测可能的 VC 性能。方法。开发了视网膜前双电极刺激的计算模型，以模拟同步和异步刺激条件下视网膜神经节细胞 (RGC) 群的神经活动。模拟了一系列刺激参数下电极和 RGC 之间的相互作用。主要结果。我们基于直接 RGC 激活的模拟表明可以使用异步刺激创建 VC。Two VC performance measures: 1) linearity in the change in centroid location of activated RGC populations, and 2) consistency in the size of activated RGC populations, have comparable performance under asynchronous and synchronous stimulation with appropriately selected stimulation parameters. 意义。我们的研究结果支持通过在同步和异步刺激条件下直接激活 RGC 来创建 VC 的可能性。本研究仅基于 RGC 群体内的时间相互作用建立了 VC 创建的基本能力，不包括任何幸存的内部视网膜网络神经元的潜在间接激活的影响。我们的研究结果为设计具有更高空间分辨率的下一代视网膜假体提供了理论依据。